System, method and apparatus for manufacturing magnetic recording media

ABSTRACT

A system, method and apparatus for manufacturing high density magnetic media is disclosed. A flexible mold having a very low modulus of less than about 4 GPa is made on a rigid support. The mold nano-imprints a resist material on disks for hard disk drives. The flexible mold may comprise a perfluoropolyether with urethane acrylate end groups with a low surface adhesion from which the cured resist is easily released.

This application is a Divisional of U.S. Utility patent application Ser.No. 12/567,277, filed Sep. 25, 2009, which is incorporated herein byreference in its entirety.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention relates in general to manufacturing magnetic mediaand, in particular, to an improved system, method and apparatus formanufacturing magnetic recording media.

2. Description of the Related Art

Patterned magnetic recording disk substrates have patterns that aretypically formed with nano-imprint lithography processes. As shown inFIG. 1, a rigid mold 11 is provided with at least the same diameter asthe disk to be patterned and is formed from a hard material, such asquartz. Curable resist 13 is applied to the rigid disk or substrate 15to be patterned, and the rigid mold 11 is pressed onto the resist.

Under pressure, the resist flows to uniformly coat the non-patternedinterstices on the disk with a uniform thickness, while also filling therecesses in the rigid mold. Radiation (e.g., UV light or heat) isapplied through the quartz to cure the resist. The rigid mold is thenseparated from the cured resist and the disk, now coated with thepatterned resist, is subsequently processed through etching andcleaning.

One problem with this technique is that when two rigid surfaces arebrought together within several hundred nanometers of each other, anyforeign hard particles 17 that are present between the surfaces affectthe pattern formed. This is particularly true for particles havingdimensions larger than the gap between the surfaces. This effect may beadvantageously utilized for some applications, such as with flat paneldisplays in the manufacturing of thin-film transistor liquid crystaldisplays. Spacer particles with precise dimensions are employed tomaintain a uniform cell gap.

The normal configuration for the resist layer 13 with uniform thicknessbetween the rigid mold 11 and the substrate 15 is shown in FIG. 1A.However, unavoidable and uncontrolled particle contamination inpatterned media manufacturing leads to tenting of the rigid mold. Thisforms a large area defect in the finished product. The defectconfiguration with an undesirable rigid particle 17 between the rigidmold 11 and the rigid substrate 15 is shown in FIG. 1B. The particlecauses an increase in the resist film thickness. The resist filmthickness variation produces features on the substrate that result inunacceptable data errors in the patterned media disk product. Thesedrawings respectively depict the rigid mold on the substrate with auniform film of resist, and the rigid mold on the substrate with a hardcontamination particle leading to a non-uniform resist film thickness.

Flexible molds for other types of nano-imprinting have been preparedfrom poly dimethyl siloxane (PDMS) such as Sylgard 184. However,PDMS-based flexible molds have limited resolution and they undergoswelling in organic solvents and resists. Flexible templates forpatterned media have been made from hydrocarbons and siloxanes. Thesedesigns present difficulties in separation from the cured resist, andhave significant durability issues since they do not last for manymolding cycles. Thus, although conventional solutions are workable forsome applications, improvements in manufacturing magnetic media would bedesirable.

SUMMARY OF THE INVENTION

Embodiments of a system, method, and apparatus for manufacturingmagnetic recording media are disclosed. In some embodiments, softlithography is used on a rigid support for making discrete track media(DTM) or bit patterned media (BPM) magnetic recording disks orsubstrates via nanoimprint lithography and dry etching. The flexiblemold mitigates the effects of hard contamination particles that preventthe uniform approach of the rigid mold and disk to be patterned with theresist in between. The flexible mold accommodates contaminationparticles with only a local deviation in the resist thicknessuniformity. In contrast, conventional soft lithography often employsmolds that are laminated onto a flexible support, like Mylar film, forroll coating. None of those solutions fabricate DTM or BPM disks using arigid support. Soft lithography for fabrication of microelectromechanical systems (MEMS) uses a small area flexible mold on arigid support to fabricate microscale devices. Soft lithography with aflexible mold on a rigid support has not been employed in fabrication ofDTM or BPM magnetic recording media.

For example, in some embodiments of soft lithography in patterned mediamanufacturing, a flexible mold having a Young's modulus of less thanabout 4 GPa is made from a rigid mold for nano-imprinting a resistmaterial. The flexible mold may comprise a multi-functionalperfluoropolyether with urethane acrylate end groups (PFPE-UA). Thesematerials may be combined with initiators, crosslinkers, extendersand/or solvents to obtain a low viscosity resin which fills a patternedmedia mold to form a thin film layer. The resin formulation film can becured by UV or heat or other means to produce a patterned media flexiblemold. The mold is easily releasable from the mold and the cured resindue to its low surface energy. In addition, alignment marks also may beprovided on the flexible mold.

The foregoing and other objects and advantages of the present inventionwill be apparent to those skilled in the art, in view of the followingdetailed description of the present invention, taken in conjunction withthe appended claims and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the features and advantages of the presentinvention are attained and can be understood in more detail, a moreparticular description of the invention briefly summarized above may behad by reference to the embodiments thereof that are illustrated in theappended drawings. However, the drawings illustrate only someembodiments of the invention and therefore are not to be consideredlimiting of its scope as the invention may admit to other equallyeffective embodiments.

FIGS. 1A and B are schematic sectional side views of a conventionalrigid mold and substrate;

FIG. 2 is a schematic sectional side view of a flexible mold on a rigidsupport showing how the flexible mold deforms around a rigid particle onthe substrate;

FIG. 3A is a sectional view of one embodiment of a mold for patternedmedia substrate manufacturing made with a flexible mold on a rigidsupport;

FIG. 3B is a closed configuration with resist between the flexible moldand the substrate during patterned media substrate manufacturing;

FIG. 4A is an optical micrograph of an embodiment of a test pattern moldin accordance with the invention;

FIG. 4B is an optical micrograph of an embodiment of a PFPE-UA flexiblemold replica of the test pattern in accordance with the invention;

FIG. 4C is an optical micrograph of an embodiment of a resist replica ofthe test pattern on the flexible mold in accordance with the invention;

FIG. 5A is an AFM image of an embodiment of a DTM rigid quartz mold inaccordance with the invention;

FIG. 5B is an AFM image of an embodiment of a PFPE-UA flexible moldreplica of the DTM rigid quartz mold in accordance with the invention;and

FIG. 5C is an AFM image of an embodiment of a resist replica of the testpattern on the flexible mold in accordance with the invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. 2-5, embodiments of a system, method and apparatusfor manufacturing magnetic recording media are disclosed. We disclosethe use of soft lithography with a rigid support for manufacturingpatterned magnetic recording media, e.g., discrete track media (DTM) orbit patterned media (BPM) magnetic recording disks or substrates viananoimprint lithography and dry etching. A flexible mold mitigates theeffects of hard contamination particles that prevent the uniformapproach of the rigid mold and disk to be patterned with the resist inbetween. The flexible mold has a low Young's modulus and has a rigidbacking material for nano-imprinting a resist material. The flexiblemold may comprise a perfluoropolyether with urethane acrylate end groups(PFPE-UA). As shown in FIG. 3B, the mold has topographical features withpredetermined width (W) and depth (D) that are reproduced in theimprints.

To overcome problems associated with conventional solutions, a rigidmold can be reproduced in a flexible polymer 9 (FIG. 2) to form aflexible mold. The flexible mold deforms around the particle 17 andalleviates the size of the defect created by particle 17 to accommodatesurface non-uniformities. FIG. 2 depicts a schematic drawing of aflexible mold 19 on a rigid support 12 with a hard contaminationparticle 17 on the substrate 15. This illustration shows how theflexible mold deforms locally to prevent a long range disturbance to thefilm thickness of the resist 13.

For example, in one experiment, replication of grooves in a recordablecompact disk (CD-R) substrate was tested with a commercial mold castingresin. For the mold, CDR substrates had their silver reflective layerremoved by cooling with liquid nitrogen which delaminated the metalliclayer from the polycarbonate. The substrates were cleaned withisopropanol (IPA) and methanol (MeOH). For a release layer, some of thesubstrates were dip-coated with Z-tetraol. Z-tetraol is aperfluoropolyether with 2 hydroxyl groups on each end, and the molecularweight was 2000 Daltons. The water contact angle was increased from 75to 100° by this release coating. Other substrates were dip-coated with aUV-cured perfluoropolyether diacrylate (PDA-Z). The water contact anglewas increased to 105° by this release coating. Commercial mold castingresins were obtained from Smooth-On Corp. These are listed in Table. 1.

TABLE 1 Commercial mold casting resins evaluated for use as flexiblemolds for patterned media. Shore Compound Type Hardness ObservationsMold Max 15T Silicone (rubber, tin cured)- A-15 Low viscosity, goodseparation fine detail, translucent w/PDA-Z, no bubbles, very flexibleSorta-Clear 40 Silicone (rubber, platinum A-40 Good separationw/Ztetraol, some catalyst) bubbles Clear-Flex 50 Polyurethane(rubber)-UV A-50 Low viscosity, few bubbles, resistant difficultseparation w/PDA-Z Ecoflex 5 Silicone (rubber) A-5  Difficult separationw/Ztetraol, did not appear to replicate as well Ecoflex 00-10 Silicone(rubber) 00-10 Good separation w/PDA-Z, too flexible Vytaflex 10Polyurethane (rubber) A-10 No separation w/Ztetraol, remained stickyafter cure Crystal Clear Urethane (plastic)-UV D-80 Difficult separationw/PDA-Z, too 202 resistant rigid

In one embodiment of a procedure and method, approximately 10 to 20grams of liquid rubber was prepared according to the instructions foreach. Several drops of each liquid rubber were squeezed between one-inchdiameter, flat poly methyl methacrylate (PMMA) disks on the grooved sideof the CD-R as a rigid mold. These were then allowed to cure overnight.The resin cured between the PMMA disk and the CD-R is the flexible mold,and the PMMA disk is the rigid support. The cured resin on the supportwas separated from the CD-R mold, and revealed a patterned side of therubber. These samples exhibited rainbow colors from the diffractionpattern of the grooves that were on the original CD-R mold.

The mold casting resins were able to reproduce the features of the CDR.They were separated by peeling, even without a release layer to lowerthe surface energy. Three resins from these trials were selected forfurther testing by replicating a discrete track media pattern rigid moldin a silicon wafer. In this experiment, the most easily removable resin,and the one that appeared to provide the best replication was Clear Flex50 (CF-50).

Spin coating of a thin flexible mold film onto a silicon wafer also wastested. The neat resin is too viscous to spin coat. The CF-50 resin wasdiluted with isopropyl alcohol to 67 wt % or 50 wt % concentration andspin coated at 1,000 or 3,000 rpm after filtration through a 0.45 micronmembrane filter. Reasonably smooth films were obtained with the 50%concentration in IPA and 3K rpm spin speed.

Quartz wafers coated with release layers of fluorinated triethoxy silanemonolayer, or perfluoropolyether, as well as uncoated wafers werepressed onto the uncured film of spin coated CF-50 resin. After theresin cured, none of the wafers could be separated from the film on thesilicon. A thin layer of resist was cured on top of the cured CF-50film, but the resist could not be separated from the cured CF-50. Inanother test, 50% CF-50 in IPA was filtered and spin coated onto afive-inch silicon wafer with a test pattern mold. The cured CF-50 couldnot be separated from the silicon.

From these results, it was determined that a release agent enhanced theuse of the hydrocarbon-based casting resin for the flexible moldapplication. With a poly dimethyl siloxane (PDMS) flexible mold, thesame release problems were reported in the literature and have beenovercome by the use of perfluoropolyether acrylates (PFPE-UA). A PFPE-UA(Solvay Solexus Corp., Fluorolink FLK MD700) was combined with 0.5% or4% of Ciba Irgacure 651 photoinitiator in Vertrel XF (with a trace ofacetone). Several drops of this solution were placed on a silicon wafer.The film was cured in UV for as long as one hour, but the resin remainedtacky. After three days in an oven at 100° C., a small bit of rubber wasformed at the edge of the wafer containing the higher amount ofinitiator. The free radical curing chemistry is inhibited by residualacetone.

The following example demonstrates embodiments of a small scalereproduction of the process to manufacture patterned media substratesfrom a flexible mold on a rigid support starting with an e-beam testpattern mold in rigid silicon. Several one-inch diameter rigid UVtransparent quartz support wafers (G.M. Associates GM-7500-01) werecleaned in a UV ozone cleaner for 5 minutes. Adhesion promoter wasapplied to the cleaned wafers by dip coating in a 1-2% solution ofmethacryloxypropyltrimethoxy silane (Gelest SIM6487.4) in ethanol with atrace of water. Excess solution was blown from the wafers with clean dryair. A solution of PFPE-UA and photoinitiator was prepared in a volatilesolvent as follows. Solvay-Solexis Fluorolink FLK5105X PFPE-UA wasdissolved at 50 wt % in DuPont Vertrel XF, and 0.7% acetone by Vertrelweight was added to facilitate dissolution of the photoiniator. Thephotoiniator was 2 wt % of Ciba Irgacure 651 by weight of Fluorolink.Several drops of the PFPE-UA solution were placed on an e-beam testpattern mold with etched submicron lines and holes made in a five-inchsilicon wafer. The solvent was evaporated to spread the PFPE-UA into afilm on the test pattern mold in a vacuum oven (800 mbar/65 C, 1 hour).The quartz support wafer coated with the adhesion promoter was pressedonto the film of PFPE-UA. The PFPE-UA was cured through the quartzsupport wafer in a UV exposure tool. The quartz support wafer coatedwith the cured flexible mold layer was peeled from the mold. There wasclean separation with low adhesion between the cured PFPE-UA and thesilicon wafer test pattern mold. The flexible mold layer was 100 micronsthick and was bonded to the quartz support wafer by the adhesionpromoter.

The surface energy of the FLK5105X flexible mold was 17.4 mN/m(calculated from measured water and hexadecane contact angles). Theindentation modulus and hardness were measured with an UltraNano-indentation tester (CSM Instruments) with a Berkovich indenter(assumed Poisson's ratio 0.5). The mechanical properties of the curedPFPE-UA flexible mold of this example are listed in Table 2. Theindentations completely recovered within seconds following the indenterload removal.

TABLE 2 Nanonindentation properties of the flexible mold from FluorolinkFLK5105X measured at two different depths in the film. maximum maximumindentation indentation load Depth hardness modulus (mN) (microns) (MPa)(MPa) 1 5 3.4 20 5 12 1.0 10

An optical micrograph of the original rigid silicon test pattern mold isshown in FIG. 4A, and an optical micrograph of the cured PFPE-UAflexible mold made from the test pattern mold is shown in FIG. 4B. Theflexible mold topography is the negative image of the original testpattern. A model resist was prepared to demonstrate replication of thetest pattern from the flexible mold. The model resist was TMPTA(trimethylol propane triacrylate, Aldrich 246840) with 2% Ciba Irgacure651 by weight of TPMTA and 1.4% acetone to facilitate dissolution of thephotoinitiator. A smooth silicon wafer was cleaned in a UV ozone cleanerfor five minutes. Adhesion promoter was applied to the cleaned wafer bydip coating in a 1-2% solution of methacryloxypropyltrimethoxy silane(Gelest SIM6487.4) in ethanol with a trace of water. Excess solution wasblown from the wafer with clean dry air. Several drops of the TMPTAresist solution were placed on the smooth silicon wafer. The solvent wasevaporated in a vacuum oven (800 mbar/65° C., one hour).

The PFPE-UA flexible mold on the rigid quartz support wafer was pressedonto the film of TMPTA on the silicon wafer. The TMPTA was cured throughthe quartz support and flexible mold in a UV exposure tool. The siliconwafer was separated from the flexible mold. There was clean separationwith low adhesion between the PFPE-UA flexible mold and the photoresist.The cured TMPTA resist layer was 50 microns thick and was bonded to thesilicon wafer by the adhesion promoter. An optical micrograph of thetest pattern in the photoresist is shown in FIG. 4C. This processreproduced the features on the original rigid silicon test pattern moldinto a resist using a PFPE-UA flexible mold held on a rigid UVtransparent support.

The next example demonstrates an embodiment of a small scalereproduction of the process to manufacture patterned media substratesfrom a flexible mold on a rigid support starting with a DTM mold inrigid quartz. The DTM quartz mold was cleaned in an oxygen plasma ashingtool (TePla M4L etcher, TePla America). The PFPE-UA formulation andprocedure was the same one used in the previous example, except that theDTM mold was substituted for the silicon test pattern mold. The DTM moldtrack pitch was 50 nm and the groove depth was 50 nm. An AFM image ofthe DTM mold is shown in FIG. 5A. The corresponding AFM image of theflexible mold replica of the DTM quartz mold is shown in FIG. 5B. Theflexible mold pattern topography is inverted relative to the originalDTM mold pattern topography.

The PFPE-UA flexible mold on the rigid quartz wafer support wasreplicated in resist on a magnetic recording disk. A commercial resistwas uniformly deposited on a magnetic disk surface treated with acommercial adhesion promoter. The flexible mold on the quartz supportwas pressed onto the film of resist, and the resist was cured throughthe quartz. The cured resist on the disk was separated from the PFPE-UAflexible mold, leaving the pattern embossed in the cured resist on thedisk. An AFM image of the cured resist pattern is shown in FIG. 5C.

The following example demonstrates a small scale reproduction of theprocess to manufacture patterned media substrates from a flexible moldon a rigid support starting with an e-beam test pattern mold in rigidsilicon, or with a DTM mold in rigid quartz using four different gradesof Fluorolink and an internal release agent. Several one-inch diameterrigid UV transparent quartz support wafers (G.M. Associates GM-7500-01)were cleaned in a UV ozone cleaner for ten minutes. Adhesion promoterwas applied to the cleaned wafers by dip coating in a 1-2% solution ofmethacryloxypropyltrimethoxy silane (Gelest SIM6487.4) in ethanol with atrace of water. Excess solution was blown from the wafers with clean dryair. Solutions of PFPE-UA and photoinitiator were prepared in a volatilesolvent. Solvay-Solexis Fluorolink FLK5110X, FLK5105X, FLK5112X, andMD700 PFPE-UA were each separately dissolved at 50 wt % in DuPontVertrel XF, and 1% acetone by Vertrel weight was added to facilitatedissolution of the photoinitiator. The photoinitiator was 1 wt % of CibaIrgacure 651 and 1% of Ciba Irgacure 819 by weight of Fluorolink.Additionally, 1 wt % of DuPont Zonyl 8857A by weight of Fluorolink wasincluded to facilitate release of the PFPE-UA flexible mold from theoriginal rigid mold and of the resist from the PFPE-UA flexible moldafter cure. The solutions were filtered through a 0.2 micron PTFEmembrane to remove solid particles. Several drops of each PFPE-UAsolution were placed on the rigid mold. The solvent was evaporated tospread the PFPE-UA into a film on the mold in a vacuum oven (800 mbar/65C, 15 to 30 min). The rigid quartz support wafer coated with theadhesion promoter was pressed onto the film of PFPE-UA. The PFPE-UA wascured through the quartz support wafer in a UV exposure tool. The quartzsupport along with the attached flexible mold layer was separated fromthe mold. The flexible mold layer remained bonded to the rigid quartzsupport wafer by the adhesion promoter.

There was improved release with low adhesion between cured PFPE-UA andthe original rigid mold with the Zonyl 8857A internal release agent. Thethickness of the PFPE-UA flexible mold layer on the quartz support waferis listed in Table 3. The Fluorolink 5110X appeared too brittle to useas a flexible mold by itself. A model resist was prepared to demonstratereplication of the test pattern on the flexible mold. The model resistwas TMPTA (trimethylol propane triacrylate, Aldrich 246840) with 1%Irgacure 651 and 1% Irgacure 819 by wt of TPMTA. A smooth silicon waferwas cleaned in a UV ozone cleaner for 5 minutes. Adhesion promoter wasapplied to the UV ozone cleaned wafer by dip coating in a 1-2% solutionof methacryloxypropyltrimethoxy silane (Gelest SIM6487.4) in ethanolwith a trace of water. Excess solution was blown from the wafer withclean dry air. Several drops of the TMPTA resist solution were placed onthe smooth silicon wafer. The PFPE-UA flexible mold on the rigid quartzsupport wafer was pressed onto the film of TMPTA on the silicon wafer.The TMPTA was cured through the quartz support in a UV exposure tool.The cured resist on the silicon wafer cleanly separated from the PFPE-UAflexible mold. The cured TMPTA resist layer remained bonded to thesilicon wafer by the adhesion promoter. The Zonyl 8857A internal releaseagent improved the release between the PFPE-UA flexible mold and theresist except with the FLK5105X which stuck to the cured resist evenwith the Zonyl additive. The process reproduced the features from theoriginal test mold into the resist using the flexible PFPE-UA mold heldon a rigid UV transparent support. Both the MD700 and the FLK5112X wereselected as suitable candidates for the PFPE-UA flexible mold. Frommicrographs taken on a 500 nm hole pattern of the resist replica, theMD700 looked better than the FLK5112X.

TABLE 3 Thickness and surface energy of the PFPE-UA flexible mold layeron the rigid quartz support wafers. Fluorolink film surface sampleoriginal thickness energy number mold (um) (mN/m) 5112X Si pattern 8017.3 MD700 Si pattern 60 17.6 5112X DTM 70 — MD700 DTM 60 —

In some embodiments, PFPE-UA materials are combined with initiators,cross-linkers, extenders, and/or solvents to obtain a low viscosityliquid that fills a patterned media mold as a thin film. The film can becured by UV, heat or other means to produce a patterned media flexiblemold. The PFPE-UA based mold is easily releasable from the mold due toits low surface energy. A coupling agent or adhesion promoter can beapplied to bond it to a rigid backing plate, possibly made from quartz,or some type of polymeric material that is rigid and UV transparent. Anopaque backing plate may be used for thermal, peroxide, epoxide or otherchemical methods of curing.

The backing plate may comprise UV-transparent quartz to allow throughexposure of the photoresist. The elastomeric, PFPE-UA based flexiblemold can then be sandwiched with a resist layer in between with amagnetic recording disk substrate which is to be coated with thepatterned resist. UV light or heat may then be used to cure the resist.The PFPE-UA mold is separated, leaving the patterned resist behind onthe substrate. The substrate is etched, cleaned, and further processedinto a patterned magnetic recording disk. The process is then repeatedwith, e.g., robotic automation to pick and place the substrates, anddeposit a cure the resist, using the same flexible PFPE-UA mold for manythousands of nearly defect-free substrates.

As an example, some embodiments provide a template 99 as shown in FIGS.3A and 3B. The template comprises a flexible imprint mold 19 on a rigidsupport 12. In an imprint lithography tool, the template transfers theinverse image that is in the mold to the imprint resist 13 on asubstrate 15. Furthermore, the flexible mold 19 cleanly separates fromthe imprint resist 13 after the resist is cured without leaving behindresidual resist on the mold 19.

In some embodiments, an imprint mold for manufacturing magneticrecording media comprises a rigid support material that isUV-transparent and has a flat surface. A flexible mold layer is locatedon the rigid support material and has a Young's modulus of less thanabout 4 GPa. The flexible mold layer comprises a perfluoropolyether(PFPE) material. The rigid support material may be flat andUV-transparent in a wavelength range of 130 to 400 nm, or in a range of250 to 400 nm. The imprint mold may further comprise an adhesion layeron the flat surface, and the flexible mold layer on the adhesion layer.The flexible mold layer may further comprise alignment targets foraligning the imprint mold with a substrate based on the alignmenttargets. The rigid support material may comprise quartz, and theflexible mold layer may have a topography that forms a topographypattern with dimensions that are precise such that one standarddeviation is less than 1 nm. The topography may comprise grooves andholes having an aspect ratio of depth to width between 0.5 and 2. ThePFPE material also may have urethane acrylate (UA) end groups, and theflexible mold layer may have a surface energy of less than 20 mN/m.

In still other embodiments, a system for imprint mold manufacturing ofmagnetic recording media comprises an imprint mold having a rigidsupport material that is UV-transparent and has a flat surface. Theflexible mold layer is on the rigid support material and has a Young'smodulus of less than about 4 GPa, with the flexible mold layercomprising a fluorohydrocarbon polymer. The imprint mold is placed incontact with a substrate having a void-free resin formulation to form atopography on the substrate. The flexible mold layer may furthercomprise optically visible alignment targets that are placed in contactand aligned with the substrate based on the optically visible alignmenttargets. The imprint mold may be removed from the substrate with resinremaining on the substrate with a compliment of the topography locatedon the imprint mold. The fluorohydrocarbon polymer comprising theflexible mold layer may have one or more urethane acrylate (UA) oracrylate pendant and/or end groups. The flexible mold layer also may beblended with at least one of mono-, di-, tri-, tetra-, andpoly-functional fluorohydrocarbon acrylates or urethane acrylates. Theflexible mold layer may be made using any other type of reactive groupsthat react to polymerize, such as epoxides or many others known to thoseskilled in the art. The imprint mold may imprint into resist, allowscure of the resist, and release from the resist without loss of thetopography.

This written description uses examples to disclose the invention,including the best mode, and also to enable those of ordinary skill inthe art to make and use the invention. The patentable scope of theinvention is defined by the claims, and may include other examples thatoccur to those skilled in the art. Such other examples are intended tobe within the scope of the claims if they have structural elements thatdo not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal languages of the claims. While the invention has beenshown or described in only some of its forms, it should be apparent tothose skilled in the art that it is not so limited, but is susceptibleto various changes without departing from the scope of the invention.

We claim:
 1. An imprint mold for manufacturing magnetic recording media,comprising: a rigid support material that is UV-transparent and has aflat surface; and a flexible mold layer on the rigid support materialand having a Young's modulus of less than about 4 GPa, the flexible moldlayer comprising a perfluoropolyether (PFPE) material.
 2. An imprintmold according to claim 1, wherein the rigid support material is flatand is UV-transparent in a wavelength range of 250 to 400 nm.
 3. Animprint mold according to claim 1, wherein the rigid support material isUV-transparent in a range of 130 to 400 nm.
 4. An imprint mold accordingto claim 1, further comprising an adhesion layer on the flat surface,and the flexible mold layer is on the adhesion layer.
 5. An imprint moldaccording to claim 1, wherein the flexible mold layer further comprisesalignment targets for aligning the imprint mold with a substrate basedon the alignment targets.
 6. An imprint mold according to claim 1,wherein the rigid support material comprises quartz, and the flexiblemold layer has a topography that forms a pattern that is precise suchthat one standard deviation of patterned dimensions is less than 1 nm.7. An imprint mold according to claim 6, wherein the topographycomprises grooves and holes having an aspect ratio of depth to widthbetween 0.5 and
 2. 8. An imprint mold according to claim 1, wherein thePFPE material has one or more urethane acrylate (UA), acrylate pendantand end groups.
 9. An imprint mold according to claim 1, wherein theflexible mold layer has a surface energy of less than 20 mN/m.
 10. Amethod of forming an imprint mold for patterned magnetic recordingmedia, comprising: providing a rigid substrate; forming an adhesionpromoter on the rigid substrate; depositing a PFPE material between therigid substrate and a substrate that has a topographical pattern;polymerizing the PFPE material; releasing the substrate with PFPEcoating with an inverse image of the topographical pattern.
 11. A methodaccording to claim 10, wherein the PFPE material comprises a urethane,acrylate, or fluorohydrocarbon material.
 12. A method according to claim10, wherein the rigid substrate is a wafer with a thickness less than 1mm.
 13. A method according to claim 10, wherein the substrate with atopographical pattern is a silicon or quartz wafer.